Investigation of the Minimum Local Analgesic Concentration of Epidural Sufentanil Combined With Ropivacaine for Labor Analgesia

ABSTRACT Purpose Worldwide, there are only few studies focusing on labor analgesia on the MLAC (minimum local analgesic concentration) or EC50 (median effective concentration) of sufentanil and ropivacaine. Therefore, we determine the MLAC or EC50 of sufentanil and ropivacaine for epidural analgesia by using an up–down sequential allocation and survey its adverse effect in a prospective blinded randomized trial. Methods Sixty nulliparous full-term parturients who required labor analgesia were recruited and randomly divided into the sufentanil and ropivacaine groups. The formulation was 25 μg sufentanil combined with 0.1% ropivacaine (added 0.9% normal saline to 75 ml). According to the response of a previous parturient, the dosage of sufentanil was increased or decreased by 5 μg in the sufetanil group; meanwhile, we also administrated an initial concentration of 0.1% ropivacaine combined with 22.5 μg sufentanil (added 0.9% normal saline to 75 ml) in the ropivacaine group. The concentration of ropivacaine was increased or decreased by 0.01% following the response of the previous parturient. The Brownlee up–down sequential allocation was used to estimate the MLAC of epidural ropivacaine and its 95% confidence intervals in labor analgesia. Findings There were no significant changes for the two groups, including for age, height weight, active stage, second stage of labor, and gestational weeks (P = 0.769, 0.900, 0.603, 0.441, 0.577, and 0.695, respectively). The VAS scores of the parturient decreased to varying degrees (P Implications The MLAC of epidural sufentanil or ropivacaine could provide satisfactory and safe analgesia for parturients while having a low incidence rate of side effects.